In data processing and/or in data transmission different lightweight and mobile devices increase in popularity. Examples of such devices are portable computers, palm computers and cellular network terminals. The display unit connected to these devices is generally realised by a technology, which makes it possible to realise a quite flat display. One example of this is an LCD display (Liquid Crystal Display). The display may also act as portion of the user interface through which instructions are entered to the actual data processing device. Then they are so called touch screens, where either a certain part or the whole display is touch sensitive, or where an obstacle placed in front of the display can be detected at the surface level of the display. Through a touch screen of this kind the device connected to the display can be controlled to perform a previously programmed function.
There are also different known solutions for electronic books or magazines, which are downloaded via a data communication network. The realisation of such solutions requires a display device, which is flexible, lightweight and has a size of at least a book page. The electronics required by the display is integrated as a part of the display. A means of this kind for displaying information may be able to operate only in a particular application, for instance only as a magazine monitor.
Hereafter the electronic devices mentioned above are called by a common term data processing device, no matter whether it is a personal computer with its display or a future electronic magazine monitor presented above.
The data processing devices mentioned above may be used and kept anywhere, as they already originally were designed to be portable and utilised in different places. For instance, if the data processing device is kept on the desk among papers and other objects, objects/obstacles may pile up on it, thus at least partly covering the device or its display. Then it will be more inconvenient to use the data processing device, as the display may be covered so that the user must first remove the disturbing obstacles in front of the display before being able to begin to use the data processing device.